<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="father">
  <h1>标题一</h1>
  <p id="p1">p1</p>
  <p class="p2">p2</p>
    <div class="child">
        <a href="https://www.baidu.com">跳转</a>
    </div>
</div>
<script>
  //类似css选择器
  var h1 = document.getElementsByTagName("h1");
  var p1 = document.getElementById("p1");
  var p2 = document.getElementsByClassName("p2");
  var father = document.getElementById("father");

  var children = father.children;//获取父节点下的所有子节点
  //father.firstChild
  //father.lastChild
  var child=document.getElementsByClassName("child");
</script>
</body>
</html>